Listen up, friends. Our bodies are all wonderfully and amazingly different, as proven simply by some of us having illnesses and chronic disease that others of us do not. Some people need one kind of medication to resolve their medical problem and others do not tolerate it. This is because our metabolism, our absorption, and our reaction to medications are different.
So, translate this into dieting. How can a diet be one size fits all if our bodies can't even tolerate synthetically constructed medications that are standardized in the same way? And how can you assume that a certain regimen of exercise is ideal for EVERYONE. This is a problematic perspective that permeates our fitness world. If you go to a certain kind of fitness class, often the instructor will encourage you to do the exercises exactly like everyone else because it worked for the instructor. News flash, that instructor's body is not identical to those she is teaching. And I am not even talking from a fitness-level perspective. I am talking deeper down: her hips are not aligned in the exact way yours are and the arch of her spine does not have the same curve as yours. Unless you are twins, I suppose. You can't assume one squat form is perfect given diversity of bodies. There are WRONG ways for everyone but there is not one right way for everyone.
So, why this soap box? One size fits all does not work in the fitness and health or even the medical world. This all is a game of trial and error to see what works for your body. If one thing isn't working, try another. Try a new diet concept, try a new fitness class. If you are getting sick on your diet, it is maybe not for you (try various styles of clean eating with more or less meat or something). Understand that the first week of a new diet will make most people not feel well, so give it some time. If you keep leaving fitness classes or your trainer with pain rather than soreness, it may be time to look for a new class. And if your doctor has had to try new regimens over and over, understand that that is because your body has not found something that works properly for it.
What can we do with this? The most important part of living a healthy lifestyle is LISTEN TO YOUR BODY. If you are hungry, eat. If you are tired, sleep. And do not eat or sleep if you are not. Stop arguing with your body and your body will thank you with health. If you feel sluggish after certain foods, cut them out. Find those foods that give you energy and you will wonderfully find that you have more energy all day and need less sleep and less caffeine.
Start simply. Eat real foods. This is not a diet, this is a choice. It is amazing to find that cutting out what I call "barcode foods" will change your life. From there, stop eating when you are full. Work out from that point by working on actually listening to your body.
As children, we have amazing hormonal feedback that tells our bodies to eat and drink when needed and not to do so if we are not hungry. As we stretch our stomachs, we lose this feedback and it becomes hard to know what our bodies need. It takes some practice, but you can retrain your body to understand this feed back. (If you want to know the science behind this, I am happy to explain farther)
Key points: listen to your body, fitness is not one sized, and eat real foods. Enjoy your healthy life :)